SGT1 Encodes an Essential Component of the Yeast Kinetochore Assembly Pathway and a Novel Subunit of the SCF Ubiquitin Ligase Complex

Kitagawa, Katsumi; Skowyra, Dorota; Elledge, Stephen J.; Harper, J. Wade; Hieter, Philip

doi:10.1016/s1097-2765(00)80184-7

Cited by 356 publications

(407 citation statements)

References 47 publications

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“…We are currently conducting yeast twohybrid assays to find possible substrates or protein partners of TaSAP5 and have identified SGT1 and HSC70 as potential interacting proteins. SGT1 was associated with components of the Skp1-Cullin-F-box protein complex in yeast and plants (Kitagawa et al, 1999;Liu et al, 2002), and HSC70 functions as a cochaperone that interacts with unfolded and denatured proteins, which are then subjected to degradation mediated by E3 ligases located in the endoplasmic reticulum (Lee et al, 2009b;Liu and Howell, 2010). Overall, TaSAP5 functioned with cooperative components by catalyzing the transfer of ubiquitin to substrate, but further research will be needed to identify the factors that enhance the protein interaction and polyubiquitin chain assembly in vivo.…”

Section: Discussionmentioning

confidence: 99%

The E3 Ligase TaSAP5 Alters Drought Stress Responses by Promoting the Degradation of DRIP Proteins

et al. 2017

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In Arabidopsis (Arabidopsis thaliana) plants growing under normal conditions, DEHYDRATION-RESPONSIVE ELEMENT BINDING PROTEIN2A (DREB2A) is present at low levels because it is ubiquitinated and destabilized by DREB2A INTERACTING PROTEIN1 (DRIP1) and DRIP2 through 26S proteasome-mediated proteolysis. Drought stress counteracts the ubiquitination and proteolysis of DREB2A, thus allowing the accumulation of sufficient amounts of DREB2A protein to activate downstream gene expression. The mechanisms leading to drought stress-mediated DREB2A accumulation are still unclear. Here, we report that the wheat (Triticum aestivum) TaSAP5 protein, which contains an A20/AN1 domain, acts as an E3 ubiquitin ligase to mediate DRIP degradation and thus increase DREB2A protein levels. Drought induces TaSAP5 expression in wheat, and TaSAP5 overexpression in Arabidopsis and wheat seedlings increased their drought tolerance, as measured by survival rate and grain yield under severe drought stress. TaSAP5 can interact with and ubiquitinate TaDRIP, as well as AtDRIP1 and AtDRIP2, leading to their subsequent degradation through the 26S proteasome pathway. Consistent with this, TaSAP5 overexpression enhances DRIP degradation and increases the levels of DREB2A protein and its downstream targets. These results suggest that TaSAP5 acts to link drought with DREB2A accumulation and illustrate the molecular mechanisms involved in this process.

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Section: Discussionmentioning

confidence: 99%

The E3 Ligase TaSAP5 Alters Drought Stress Responses by Promoting the Degradation of DRIP Proteins

et al. 2017

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“…In a recent publication, the ubiquitin ligase E6-AP was also shown to be associated with Hsc/Hsp70 and to participate in the ubiquitylation and degradation of chaperone clients (Mishra et al, 2009). The interaction of Hsp90 with SGT1, an interactor of the hetero oligomeric SCF ubiquitin ligase complex, points to yet another ubiquitin conjugation machinery that could potentially be involved in CAP (Kitagawa et al, 1999;Mayor et al, 2007;. Finally, the small heat shock protein a-B crystallin that is overexpressed in many neurological diseases was shown to associate with the SCF complex adaptor Fbx4 and to stimulate the Fbx4-mediated ubiquitylation of as yet to be identified substrate proteins (den Engelsman et al, 2003).…”

Section: Figurementioning

confidence: 99%

Chaperone-assisted degradation: multiple paths to destruction

Kettern

Dreiseidler

Tawo³

et al. 2010

Biological Chemistry

154

155

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Molecular chaperones are well known as facilitators of protein folding and assembly. However, in recent years multiple chaperone-assisted degradation pathways have also emerged, including CAP ( haperone-ssisted roteasomal degradac a p tion), CASA ( haperone-ssisted elective utophagy), and c a s a CMA ( haperone-ediated utophagy). Within these pathc m a ways chaperones facilitate the sorting of non-native proteins to the proteasome and the lysosomal compartment for disposal. Impairment of these pathways contributes to the development of cancer, myopathies, and neurodegenerative diseases. Chaperone-assisted degradation thus represents an essential aspect of cellular proteostasis, and its pharmacological modulation holds the promise to ameliorate some of the most devastating diseases of our time. Here, we discuss recent insights into molecular mechanisms underlying chaperone-assisted degradation in mammalian cells and highlight its biomedical relevance.

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“…Studies from several groups indicated that SGT1 is required by a diverse range of R genes from different plant species in response to a variety of pathogens [61,[92][93][94][95]. In yeast, SGT1 is a key regulatory protein in centromere function and cell cycle transition and is associated with SKP1 to regulate the activity of the SCF E3 ligase complex [96]. Thus it is speculated that SGT1 functions in plant defense by regulating the activity of the yet unknown SCF E3 ligase that regulates plant defense signal transduction.…”

Section: U-box-type E3 Ligases Are Newly Identified Members Of the Ubmentioning

confidence: 99%

Ubiquitination-mediated protein degradation and modification: an emerging theme in plant-microbe interactions

et al. 2006

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Post-translational modification is central to protein stability and to the modulation of protein activity. Various types of protein modification, such as phosphorylation, methylation, acetylation, myristoylation, glycosylation, and ubiquitination, have been reported. Among them, ubiquitination distinguishes itself from others in that most of the ubiquitinated proteins are targeted to the 26S proteasome for degradation. The ubiquitin/26S proteasome system constitutes the major protein degradation pathway in the cell. In recent years, the importance of the ubiquitination machinery in the control of numerous eukaryotic cellular functions has been increasingly appreciated. Increasing number of E3 ubiquitin ligases and their substrates, including a variety of essential cellular regulators have been identified. Studies in the past several years have revealed that the ubiquitination system is important for a broad range of plant developmental processes and responses to abiotic and biotic stresses. This review discusses recent advances in the functional analysis of ubiquitination-associated proteins from plants and pathogens that play important roles in plant-microbe interactions.

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SGT1 Encodes an Essential Component of the Yeast Kinetochore Assembly Pathway and a Novel Subunit of the SCF Ubiquitin Ligase Complex

Cited by 356 publications

References 47 publications

The E3 Ligase TaSAP5 Alters Drought Stress Responses by Promoting the Degradation of DRIP Proteins

The E3 Ligase TaSAP5 Alters Drought Stress Responses by Promoting the Degradation of DRIP Proteins

Chaperone-assisted degradation: multiple paths to destruction

Ubiquitination-mediated protein degradation and modification: an emerging theme in plant-microbe interactions

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